Lipidomic Response of Poa pratensis cv. Qinghai to Drought Stress

Poa pratensis cv. Qinghai, an ecologically important forage grass cultivar of P. pratensis, plays a significant role in grassland ecosystems. In plant stress physiology, lipids play essential roles in cellular signaling, membrane integrity, and metabolic adaptation to environmental stress. However, lipid metabolism in P. pratensis cv. Qinghai remains insufficiently explored. To address this gap, this study systematically profiled lipid metabolites under different levels of drought stress using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 1006 and 1023 lipid species were identified in leaves and roots, respectively, and classified into 30 subclasses belonging to six major categories. The most abundant lipid subclasses in both tissues were triacylglycerol (TG), diacylglycerol (DG), phosphatidylethanolamine (PE), and phosphatidylcholine (PC). A total of 585 and 433 differentially accumulated lipid metabolites were identified in leaves and roots, respectively. Sixteen metabolic pathways were annotated using the KEGG database, nine of which were directly associated with lipid metabolism. Based on enrichment factors and statistical significance (p < 0.05), the glycerolipid and glycerophospholipid metabolism pathways were identified as the primary pathways responding to drought stress in leaves and roots. By integrating pathway enrichment analysis with fold-change thresholds (|log2FC| ≥ 1, adjusted p < 0.05), DG and TG were identified as key metabolites in the glycerolipid metabolism pathway, whereas phosphatidylserine (PS) and phosphatidylethanolamine (PE) were identified as key metabolites in the glycerophospholipid metabolism pathway under drought stress. This study proposes a regulatory network of lipid metabolism in P. pratensis cv. Qinghai under drought stress and provides new insights into lipid remodeling mechanisms. The identified key lipids and metabolic pathways improve the understanding of drought adaptation and may provide a basis for developing strategies to enhance stress tolerance in forage grasses.